Download or read book Final Report on the Analysis of Crack Growth Initiation Propagation and Arrest in Flawed Ship Structures Subjected to Dynamic Loading to Mechanics Division Office of Naval Research written by C. R. Barnes and published by . This book was released on 1984 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Final Report on the Analysis of Crack Growth Initiation Propagation and Arrest in Flawed Ship Structures Subjected to Dynamic Loading written by United States. Office of Naval Research and published by . This book was released on 1984 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Analysis of Crack Growth Initiation Propagation and Arrest in Flawed Ship Structures Subjected to Dynamic Loading written by C. R. Barnes and published by . This book was released on 1984 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work represents a systematic experimental and analytical approach to extend state-of-the-art fracture mechanics treatment of crack initiation, propagation, and arrest in tough ductile materials such as ship steels. A dynamic nonlinear finite element analysis was devised to attack the problem on a step-by-step basis. The program began to work on a high strength 4340 steel under mechanical impact conditions. Then, as a degree of understanding was achieved, more realistic conditions were treated. (Author).
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1984-12 with total page 1194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamic Crack Propagation in Precracked Cylindrical Vessels Subjected to Shock Loading written by C. H. Popelar and published by . This book was released on 1979 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous work has shown that a speed-independent dynamic fracture toughness property can be used in an elastodynamic analysis to describe crack initiation and unstable propagation under impact loading. In this paper, a further step is taken by extending the analysis from simple laboratory test specimens to treat more realistic crack-structure geometries. A circular cylinder with an initial part-through wall crack subjected to an impulsive loading on its inner surface is considered. The crack is in a radial-axial plane and has its length in the axial direction long enough that a state of plane strain exists at the center of the crack. Crack growth initiation and propagation through the wall is then calculated. It is found that, once initiated, crack propagation will continue until the crack penetrates the wall. Crack arrest within the wall does not appear to be possible under the conditions considered in this paper. (Author).
Download or read book Crack Arrest Methodology and Applications written by George T. Hahn and published by ASTM International. This book was released on 1980 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Crack Turning in Fracture in Ship Structures written by and published by . This book was released on 2001 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report investigates the ability to predict crack propagation in a ship structure by finite element analysis based on linear elastic fracture mechanics. The investigation studied whether the stress intensity factor at the crack tip, the number of cycles of constant amplitude loading to reach the critical intensity factor, and the critical length of the crack could be accurately predicted. The investigation concentrated on the ability to predict crack turning during propagation. Cracks originating at a plate edge, at a hole, and in the centre of a plate were evaluated. The results demonstrated the load & stress conditions under which crack turning was most likely to occur.
Download or read book Dynamic Crack Propagation Through Welded HY 80 Plates Under Blast Loading written by J. Ahmad and published by . This book was released on 1985 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A systematic approach involving experiments and dynamic elastic-plastic finite element analyses was used to investigate the problem of crack initiation, propagation, and arrest in weldments under rapidly applied loading. The aim was to develop a predictive capability that can be used to assess the risk of fracture in welded structures subjected to blast loading. The experimental effort included residual stress measurements on welded HY-80 steel specimens together with a series of explosive loading experiments performed after precracking these specimens. Measurements were made of the time of crack growth initiation and the extent of crack growth at arrest. Elastic-thermoplastic finite element computations were made to obtain the weld-induced residual stresses. With these as initial conditions, dynamic elastic-plastic computations were then performed to predict crack initiation and growth behavior under the measured explosive loading history. These computations used estimates of the running fracture toughness based on fracture toughness data for HY-80 weldments available in the literature. Reasonably good agreement was obtained with the observed results. Of possible greater significance for subsequent fracture mechanics analyses of weld defect problems, it was found that the presence of weld-induced residual stresses strongly affects the prediction of the crack length at arrest.
Download or read book Crack Propagation and Arrest in Ship and Other Steels written by George T. Hahn and published by . This book was released on 1970 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crack Propagation and Arrest in Ship and Other Steels written by and published by . This book was released on 1971 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: The program was undertaken to explore the possibility of measuring and analyzing crack propagation and arrest. These processes depend on a number of factors: (1) the mechanics of the flawed structure (or test specimen), (2) the plastically deformed zone at the crack tip, (3) the metal's resistance to plastic flow and its rate dependence, and (4) the processes of cleavage and ductile rupture on the microstructural scale. The work sought numerical descriptions of the individual factors with the aim of assembling these into a comprehensive, systems-type analysis of propagation and arrest. The studies employed the DCB (double-cantilever-beam) test specimen because this configuration offers the possibility of initiating, propagating, and arresting a fast fracture, under controlled conditions, within the confines of a single specimen. Analyses of the stress fields of stationary cracks in DCB specimens are reported. (Author).
Download or read book Experimental and Numerical Study of Dynamic Crack Propagation in Ice Under Impact Loading written by Lan Yao and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomena relating to the fracture behaviour of ice under impact loading are common in civil engineering, for offshore structures, and de-ice processes. To reduce the damage caused by ice impact and to optimize the design of structures or machines, the investigation on the dynamic fracture behaviour of ice under impact loading is needed. This work focuses on the dynamic crack propagation in ice under impact loading. A series of impact experiments is conducted with the Split Hopkinson Pressure Bar. The temperature is controlled by a cooling chamber. The dynamic process of the ice fracture is recorded with a high speed camera and then analysed by image methods. The extended finite element method is complementary to evaluate dynamic fracture toughness at the onset and during the propagation. The dynamic behaviour of ice under impact loading is firstly investigated with cylindrical specimen in order to obtain the dynamic stress-strain relation which will be used in later simulation. We observed multiple cracks in the experiments on the cylindrical specimens but their study is too complicated. To better understand the crack propagation in ice, a rectangular specimen with a pre-crack is employed. By controlling the impact velocity, the specimen fractures with a main crack starting from the pre-crack. The crack propagation history and velocity are evaluated by image analysis based on grey-scale and digital image correlation. The main crack propagation velocity is identified in the range of 450 to 610 m/s which confirms the previous results. It slightly varies during the propagation, first increases and keeps constant and then decreases. The experimentally obtained parameters, such as impact velocity and crack propagation velocity, are used for simulations with the extended finite element method. The dynamic crack initiation toughness and dynamic crack growth toughness are determined when the simulation fits the experiments. The results indicate that the dynamic crack growth toughness is linearly associated with crack propagation velocity and seems temperature independent in the range -15 to -1 degrees.
Download or read book Approximate Methods for Analysis of Dynamic Crack Growth and Arrest written by F. Nilsson and published by . This book was released on 1988 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Approximate methods that are less time-consuming than finite-element method (FEM) analysis are needed for dynamic crack propagation and arrest calculations. In this context the one-dimensional wave propagation models, where the cracked section is modeled by a flexibility matrix, may be a reasonable alternative. Such models are compared with fully dynamic two-dimensional FEM calculations of experimentally observed crack growth histories in an edge-cracked rectangular sheet. A fairly good agreement is obtained; the discrepancies could mainly be ascribed to differences in the end conditions. The author concludes that spring models are worth further examination in order to make them a practical tool for engineering design analysis.
Download or read book A Study of Subcritical Crack Growth in Ship Steels written by Philip H. Francis and published by . This book was released on 1975 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents an evaluation of the potential problems associated with crack initiation and subcritical crack growth in high strength, low alloy steels used in welded ship structure. An interpretive review of the state-of-the-art is given, emphasizing design tools that are available and their potential for use in fail safe or safe crack growth ship design philosophy. A crack initiation and crack growth Criterion is presented, which permits welded ship structure to be designed with confidence that serious failures can be avoided, while at the same time full use of the attractive static properties of HSLA steels can be exploited. The report also includes a list of problem areas in need of further clarification in order to enhance confidence in the proposed Criterion.
Download or read book Fatigue Crack Growth written by Alphonse F. Lignelli and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue is one of the primary reasons for the failure of structural components. The life of a fatigue crack has two parts, initiation and propagation. Dislocations play a major role in the fatigue crack initiation phase. It has been observed in laboratory testing that after a large number of loading cycles dislocations pile up and form structures called persistent slip bands (PSB). Fatigue crack growth is a crucial subject in the aircraft, railroad and other transportation industries as well as in the biomedical industry. This book presents the latest research in the field.
Download or read book Experimental Research on Explosively Driven Crack Initiation and Propagation from Flaws of Various Geometry written by Renshu Yang and published by . This book was released on 2020 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this study is to explore the fracture dynamic properties of defect bodies under explosion loading by using the system of digital laser dynamic caustics test. The propagation of directional cracks and the fracture process of defect bodies have been observed by high-speed camera, as well as analyzed for the changing rules of speed and stress intensity factors when the directional crack was close to defect. Experimental results found that the defect has an inhibitory effect on the spreading of cracks when the detonation crack is extended toward the defect. With the decrease of the curvature of the elliptical defect, the energy accumulation rate decreases with the decrease of the curvature in the process of the generation of the cracks at the endpoints of wings, and its fracture toughness increases with the decrease of the curvature, and when the curvature is reduced to a certain extent, the wing crack cannot crack. The dynamic stress intensity factor of the crack tip has a positive correlation with the velocity of cracking, within a certain range. The fracture toughness of the crack at the time it begins is larger than during its spreading.
Download or read book Generic Approaches to Risk Based Inspection Planning for Steel Structures written by Daniel Straub and published by vdf Hochschulverlag AG. This book was released on 2004 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Growth Analysis of Structures Exposed to Fluids with Oscillating Temperature Distributions written by S. Chattopadhyay and published by . This book was released on 1993 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation considers amplitudes and frequencies of the oscillating temperature distribution as parameters for crack propagation studies. The alternating stresses produced by the temperature distribution are used to determine the ranges of stress intensity factors for a particular crack geometry using the principles of linear elastic fracture mechanics. The crack growth is then studied using a crack growth law for the material relating the crack growth per cycle to the number of cycles.
